Volumetric flow in the umbilical artery: Normative data

Abstract

Objective Provide normative data for the volumetric blood flow (cc/min and cc/min/kg) in the umbilical artery. Methods Flow was determined from an umbilical artery in 252 normal obstetrical patients from 18–40 weeks' gestation utilizing pulsed Doppler and color flow Doppler with an angle of insonation of 30–60°. Simultaneous velocimetry studies (S/D ratio, resistance and pulsatility indices), fetal biometry, and an anatomic survey were obtained to further define the normal population. Results There was a steady increase in the flow (cc/min) in the umbilical artery as pregnancy progressed. Flow/kg showed a steady decline as fetal weight increased. Umbilical artery diameter increased until reaching a plateau at 32–34 weeks. Velocimetric results were consistent with known data. Conclusions Volumetric blood flow in the umbilical artery can be determined with relative ease and normative data from 18–40 weeks is presented for the first time. J. Matern.-Fetal Med. 9:224–228, 2000. © 2000 Wiley-Liss, Inc.